Mineral concentration



Patented June 6, 1933 UNITED STATES OFFICE ARTHUR CRAGO AND HAROLD S. MARTIN, OF l'dULBEB-RY, FLORIDA, ASSIGNORS TO PHOSPHATE RECOVERY CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE No Drawing.

This invention relates to mineral concentration and reagents therefor and is herein described as embodied in processes which are carried out for the concentration of the phosphate content of phosphate-bearing ore.

Phosphates have already been successfully concentrated with the aid of fuel oil when agitated in a pulp which also contains soap, but it has been supposed that the only soaps capable of successful use had to be made of fairly expensive materials, and it has h1therto been deemed impossible to concentrate phosphates with the aid of soap made from such substances as palm oil, cotton-seed o l foots, olive oil foots and some cocoanut 011 products, oil foots being the organic matters that settle out on standing.

According to the present invention as herein illustrated, the phosphate-bearing g material is agitated in a pulp contannng a substantially insoluble and unsaponifiableoil which carries fatty acids in solution. It is found that, under these conditions, fatty acids derived from such sources as have been mentioned above are not only almost as efficient as the more expensive oleic acid but may even be more efiicient.

The fatty acid is usually dissolved in warm fuel oil or warm Diesel engine oil and then the reagent thus obtained is added to the pulp in any suitable manner. Under these conditions it is found that a less quantity of the fatty acid Will often suffice than that which has been hitherto added, either as oleic acid or in the form of soap, and it is also found that a less quantity of unsaponifiable insoluble oil than has hitherto been'deemed necessary is effective. It has also been found possible to obtain larger re- 40 coveries than were hitherto deemed possible and yet obtain equally rich concentrates.

It has been found that the best results are obtained when the fatty acids used are the higher fatty acids which form substantially insoluble calcium soaps. The resin acids or the acids of American rosin are usually less efiective than the other acids unless used in a larger quantity than is necessary when some other acids are used.

Some of the .acids, such as palmitic,

MINERAL CONCENTRATION Application filed October 14, 1931. Serial No. 568,864.

stearic, ricinoleic acid, usually fail to produce a sufficient quantity of bubbles in the pulp water to render the process efficient, and when such fatty acids are used it is often desirable to add pine oil, resin oil or a tar acid or other frothing agent to serve as a bubble-producing agent.

Satisfactory results have been obtained when the process was carried out with the fatty acids obtained from fish oil, menhadcn oil, corn oil cotton oil, cotton-seed foots, linseed oil, olive foots, castor oil,.peanut oil, soy bean oil and palm oil. In addition to the acids named above, these oils contain either linoleic, linolenic, inyristic, clupanodonic or arachidic acids. Usually co'coanut oil contains a considerable percentage of soap-forming acids of low molecular Weight, and a larger quantity of the acids obtained from such oil has to be used than is neces sary when using other fatty acids. The, same is true of some other acids such as caprylic acid.

- It has been found that the dividing line between acids which work effectively and those that only work when used in excessive quantities is fairly well defined by the line drawn at the acids containing 12 carbon atoms, the acids containing less than 12 carbon atoms usually proving unsatisfactory .or expensive to use. Dihydroxy fatty acids often have proved as useful as monohydroxy acids.

When suitable fatty acids are dissolved in the unsaponifiable oil, such as fuel oil, and I then added to the pulp, it is found unnecessary to add soap as such; but the desired result can be obtained by agitating, in the presence of alkali, the pulp containing the fatty acids dissolved in fuel oil. Moreover, it is found that the alkali used may work satisfactorily even if it is some form of soda, despite the fact that it has hitherto been deemed necessary to use the potassium soaps of certain fatty acids because of the relative insolubility of the corresponding sodium soaps.

If the process is worked in Florida in hot weather, it has been found satisfactory to dissolve the solid fatty acids obtained 100 from fish oil in a fuel oil of 20 B. and to use this solution in the phosphate pulp. In cold weather it was found advantageous to use a lighter gravity oil. The mixed fish oil fatty acids are solid at ordinary temperatures, but become perfectly fluid at a temperature of 100 to 125 F. If they are warmed until fluid and then stirred into the warm hydrocarbon oil there usually results a uniform and homogeneous mixture which throws down only a small amount of solids when cooled to atmospheric temperatures.

It is found that the best results are usually obtained when the fatty acids are warmed with about an equal weight of the fuel or other oil and introduced in that solution, in emulsion if desired, into a pulp which has already been treatedwith caustic soda. The best results have been obtained when the caustic soda was added in a 5 to 10% solution in sufiicient quantity to produce a pH value of 8.0 to 9.6 in the pulp, though other alkalis, such as trisodium phosphate and ammonia and some amines give very good results.

It has been found most eqmomical to first deslime the pulp so as to separate out all material smaller than 200 to 300 mesh and then treat the deslimed sands in a pulp containing from to 60% water with the caustic soda and to add the solution of fatty acid and fuel oil after agitating the alkalinized pulp. Usually about 0.3 to 1.5 lbs.

of caustic soda per ton of dry feed were satisfactory.

In treating Florida rock the debris or waste material from the rock washers, ranging in size from 4" down to slimes, was screened. The usual screen Was a 20, 28 or 35-mesh sieve, and the over-size was ground in a rod mill to pass the same sieve, added to the original undersize and the whole reagitated with water. The agitated pulp was allowed to stand for a short period and the suspended slime decanted off. In laboratory work decantation is usually carried out two or three times. The caustic soda was added to the deslimedpulp in solution as described above and enough of the solution of fatty acid and fuel oil was added so as to add from 0.25 to 2.0 lbs. of free acid per ton of feed, and the pulp agitated. Later further fuel-oil was added, usually enough to bring up the total fuel oil to 1 to 7 lbs. per ton of dry feed. Then a frothing agent, such as Hercules Powder Compa'nys Tarol #2 was added in an amount equal to 0.1 to 0.3 lbs. per ton of dry feed. After further agitation the thick pulp was introduced into the flotation machine, diluted with tap water and a float when agitated to produce formed rapidl aeration. U11 er proper oondltions in a Minerals Separation Subaeratmn laboratory machine a satisfactory float was obtained in from one to four minutes.

Crystalline forms of calcium phosphate, I

ditions if much material finer than 300 mesh is present there is an increased consumption of reagents when a satisfactory concentration is obtained. Moreover, there is often required a longer time to obtain the float.

It is generally found best to keep the phosphate particles as much as possible between 35 mesh and +100 mesh and exclude substantially all of 300 mesh.

A series of tests were carried on in the laboratory with various fatty acids using as phosphate-bearing materials a well mixed sample of flotation feed from the Phosphate Recovery 'Corporation N o. 2 Plant at Mulberry, Florida, which was of the type described above. Ineach case a rougher concentrate was floated off for one minute, the tailings withdrawn, the rougher concentrate replaced in the machine and diluted and refloated, without addition of further reagent, for one minute.

The tailing from the cleaning operation was weighed and assayed separately, but added to the rougher tailing in calculating file recovery of tricalcium phosphate (B. P.

Test N 0. 1.'-Semisolid fatty acids of castor oil were dissolved in anequal volume of 20 B. fuel oil by warming and stirring, and added to the alkalinized pulp after cooling to room temperature. One pound of the fatty acids dissolved in fuel oil per ton of solids was added to a pulp made of the above-described flotation feed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pound per ton of Tarol #2, (a mixture of 75% steam distilled pine oil and 20% rosin oil by volume) the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a minute and a finished concentrate separated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other .tailings in this test. The calculated heads contained 32.89 B. P. L., the concentrates contained 70.05 and the middlings and tailings contained 5.31% B. P. L., representing a recovery of ,90.7 and a ratio of concentration of 2.35.

Test N 0. 2.'Liquid fatty acidsof cocoanut oil were dissolved in an equal volume of 20 B. fuel oil by warming and stirring and added to the alkalinized pulp after cooling to room temperature. 1.5 lbs. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a pulp made of the above-described flotation 'feed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a. minute and a finished concentrate separated. The tailings from the cleaning operation were midacids dissolved in fuel oil, per ton of solids,

wa s addedto a pulp made of the above-described flotation feed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added .14 pound per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a minute and a finished concentrate separated. The tailings from the cleaning operation weremiddlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 33.05% B. P. L, the concentrates contained 73.31% and the middling and tailings contained 4.5%-B. P L, representing a recovery of 92% and a ratio of concentration of 2.41. i

Test N0. 4.'Solid fatty acids of cotton seed oil foots were dissolved in an equal volume of 20 B. fuel oil, by warming and stirring, and added to the alkalinized pulp after cooling to room temperature. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a pulp made of the above-described flotation feed, and there after enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pound per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a minute and a finished concentrate separated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 33.03% B. P. L., the concentrates contained 73.91% and the middling and tailings contained 5.32% B.

P. L., represen ing a recovery of 90.4% and a ratio of concentration of 2.48.

Test No. 5 .'Solid fatty acids. of fish oil were dissolved in an equal volume of. 20 B. fuel oil, by warming and stirring, and added to the alkalinized pulp after cooling to room temperature. 0.3 lbs. of the fatty acids dissolved in fuel oil, per' ton of solids, was added to a pulp made of the above-described flotation feed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a minute and a finished concentrate separated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 32.7% of B. P. L., the concentrates contained 72.91% and the middling and tailings contained 5.45% B. P. L., representing a recovery of 90.1 and a ratio of concentration of 2.48. 1

Test 1V0. 6:Liquid fatty acids of linseed oil were dissolved in an equal volume of 20 Be. fuel oil, by warming and'stirring, and added to the alkalinized pulp after cooling to room temperature. 0.31 lbs. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a pulp made of the above-described flotation feed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a minute and a finished concentrate separated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 32.10% B.-P. L., the concentrates contained 72.85% and the middling and tailings contained 4.44% B. P. L., representing a recovcry of 92.2 and a ratio of concentration of 2.39.

Test N0. /":S0lid fatty acids of palm oil were dissolved in an, equal volume of 20 B. fuel oil, by warming and stirring, and added to the alkalinized pulp after cooling to room temperature. 0.75 lbs. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a pulp made of the abovedescribed flotation feed, and thereafter enough fuel oil added to bring the total fuel Olil up to two pounds per ton. added 0.14 pounds per ton of Tarol #2, this pulp agitated for One minute, and a rougher -float concentrate separated. This concentrate was then diluted with further water,

There was the above-described flotation reagitated for a minute and a finished concentrate separated. The tailin s from the cleaning operation were mid lings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 33% B. P. L. the concentrates contained 72.49% and the middling and tailings contained 3.44% B. P. L., representing a recovery of 94.% and a ratio of concentration of 2.34.

.Test N0. 8.--Semi-solid fatty acids of peanut oil were dissolved in an equal volume of 20? B. fuel oil, by warming and stirring, and added to the alkalinized pulp after cooling to room temperature. 0.7 lbs. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a ulp made of the above-described flotation eed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further Water, reagitated for a minute and a finished cencentrateseparated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 32.64% B. P. L., the concentrates contained 73.93% and the middling and tailings contained 8.28% B. P. L., representing a recovery of 84.% and a ratio of concentration of 270. I

Test N0. .9:Liquid fatty acids of soya bean oil were dissolved in an equal volume of 20 fuel oil, by warming and stirring, and added to the a'lkalinized pulp after cooling toroom temperature. 0.3 lbs. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a pulp made of the above-described flotation feed, and thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the ulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated fora minute and a finished concentrate separated. The tailings 'from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 32.84% B. P. L., the concentrates contained 73.11% and the middling and tailings contained 4.03% B. P. L., representing a recovery of 92.8% and a ratio of concentration of 2.53.

Test N0. 10:Liquid fatty acids from olive oil foots were dissolved in an equal volume of 20 B. fuel oil, by warming and stirring, and added to the alkalinized pulp after cooling to room temperature. 0.45 lbs.

of the fatt acids dissolved in fuel oil, per ton of soli s, was added to a pul made of eed, and

thereafter enough fuel oil added to bring the total fuel oil up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for a minute and a finished concentrate separated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads contained 32.58% B.P.L., the concentrates contained 73.82% and the middling and tailings contained 4.47% B.P.L., representing a recovery of 91.8% and a ratio of con entration of 2.47.

Test N0. 11 :Solid fatty acids of tung oil were dissolved in an equal volume of 20 B. fuel oil, byfwarming and stirring, and added to the alkalini'zed pulp after cooling to room temperature. 0.5 lbs. of the fatty acids dissolved in fuel oil, per ton of solids, was added to a pulp made of the abovedescribed flotation feed, and thereafter enough fuel oil added to bring the total fuel 011 up to two pounds per ton. There was added 0.14 pounds per ton of Tarol #2, the pulp agitated for one minute, and a rougher float concentrate separated. This concentrate was then diluted with further water, reagitated for one minute and a finished concentrate separated. The tailings from the cleaning operation were middlings capable of being retreated, but added to the other tailings in this test. The calculated heads tontained 32.53% B.P.L., the concentrates contained 74.24% and the middling and tailings contained 4.84% B.P.L., representing a recovery of 91.1% and a ratio of concentration of 2.5.

Having thus described certain embodiments of the invention, what is claimed is:

1. The process of concentrating a phosphate-bearing material which consists in agitating a pulp of the material with a petroleum oil carrying fatty acid in solution so as to produce a float, and separating the float.

2. The process of concentrating a phosphate-bearing material which consists in agitating a pulp of the material with a heavy petroleum oil carrying fatty acid in solution so asto produce a float, and separating the float.

3. The process of concentrating a phosphate-bearing material .which consists in agitating analkaline pulp of the material with a petroleum oil carrying fatty acid in solution so as to produce a float, and separating the float.

4. The process of concentrating a phosphate-bearing material which consists in agitating an alkaline pulp of the material with a heavy petroleum oil carrying norwhose molecules include more than 12 carbon atoms, so as to produce a float, and separating the float.

p The process of concentrating a phosphate-bearing material which consists in agitating an alkaline pulp of the deslimed material with a petroleum oil carrying normally solid fatty acid in solution so as to produce a float, and separating the float.

8. The process of concentrating a phosphate-bearing material which consists in agitating an alkaline pulp of the deslimed material with a heavy petroleum oil carrying in solution a nearly equal amount of the fatty acids obtained from oil fcots so as to produce a float, and separating the float.

9. The process of concentrating a phosphate-bearing material which consists in agitating a thick alkaline pulp of the material with a heavy petroleum 011 carrying fatty acids in solution, diluting the pulp, agitating' the pulp so as to produce a float, and separating the float.

10. The process of concentrating a phosphate-bearing material which consists in agitating a thick pulp 'of the deslimed material with caustic soda, further agitating the pulp with a small quantity of heav petroleum oil carrying fatty acid in solution, diluting the pulp, agitating the diluted pulp with the further addition of a frothing agent so as to produce a float, and separating the float.

11. The process of concentrating a phosphate-bearing material which consists in agitating a pulpof the deslimed material with. caustic soda, further agitating the pulp with a small quantity of heavy petroleum oil-carrying in solution nearly an equal amount of solid fatty acid, diluting the pulp, agitating the diluted pulp with the further addition of a frothing agent so as to produce a float, and separating the float.

12. The process of concentrating a phos-fl phate-bearing material which consists in a tating an alkaline pulp of the material with a heavy petroleum oil carrying normally solid fatty acids of cottonseed oil foots in solution so as to produce a float, and separating the float. 4

13. The process of concentrating a phosphate-bearing material which consists in agitating an alkaline pulp of the material with a heavy petroleum oil carryin normally solid fatty acids of fish oil in so ution so as to producea float, and separating the float.

In testimony whereof, we have signed this specification.

ARTHUR CRAGO. HAROLD S. MARTIN. 

